Riding gang mowers using reel type cutting units are well known for cutting grass. Such mowers deploy a plurality of reel cutting units that are arranged relative to one another to cut a large, unbroken swath of grass during a single pass of the mower over the ground. Usually, a plurality of reel cutting units is disposed in a front row with one or more reel cutting units also being disposed in a rear row that trails the front row taken with respect to the forward direction of motion of the mower. The front cutting units usually outnumber the rear cutting units (e.g. 2 to 1 in a triplex configuration or 3 to 2 in a fiveplex configuration). The front cutting units are laterally spaced apart from one another with gaps being present between the front cutting units. The trailing rear cutting units are also laterally spaced apart from one another, but are positioned so that the ends of the rear cutting units overlap the ends of the front cutting units that are in the interior of the swath to completely cover the gaps between the front cutting units to avoid leaving uncut strips of grass in the cut swath.
In known reel type gang mowers, the front and rear cutting units have the same width. The width of the cutting units can vary from one mower model to another mower model. For example, some mowers might have relatively small cutting units each of which provides 18″ of cutting width while other mowers might have relatively large cutting units each of which provides a 27″ cutting width. Obviously, mowers having reel cutting units with wider cutting units will cut a larger swath of grass than mowers having reel cutting units with smaller cutting widths when the mowers each have the same number of cutting units. However, it has always been the case in the mower art that once a particular size of cutting units has been selected for use on a particular mower model, all the cutting units used on that mower model, whether front cutting units or rear cutting units, will be the same size.
When reel gang mowers cut grass in a straight swath while moving straight ahead in a forward direction, the designed or nominal overlap provided between the front and rear reel cutting units will be sufficient to cover whatever gaps exist between the front cutting units so that the cut grass swath is unbroken. However, the Applicants have discovered that uncut strips of grass begin to appear in the cut grass swath in at least some of the gaps between the front cutting units when reel gang mowers turn to the left or the right depending on the severity of the turn. In other words, the Applicants have discovered that the nominal overlap of the rear cutting units with the sides of the front cutting units disappears in some of these turning situations with some gaps now appearing in place of the overlaps. Uncut strips of grass are now left in these intermittent or temporary gaps that can appear when the reel gang mowers are turning.
The Applicants have also discovered other mowing situations where such intermittent or temporary gaps appear and leave uncut strips of grass in the cut grass swath. These other mowing situations include S turns by the mower where the mower first turns to one side and then substantially immediately thereafter turns back to the other side. Another such mowing situation is mowing along a sidehill where the mower traverses a fairly steep sidehill by driving in a laterally direction across the sidehill. In this sidehill mowing situation, the back of the cutting units tend to crab or tilt down the sidehill with the backs of the rear cutting units crabbing or tilting downhill somewhat further than the backs of the front cutting units. In both the S turn and sidehill mowing situations described above, the Applicants have discovered that gaps will appear between some of the sides of the rear cutting units and several of the interior sides of the front cutting units, leading again to uncut strips of grass in the cut grass swath.
Traditionally, the prior art approach in reel gang mower design has been to keep the overlap between the front and rear cutting units as small as possible for various reasons. First, a small overlap increases the width of the cut grass swath using identical sized cutting units, thereby increasing mower productivity. Second, a small overlap results in keeping the gaps between the laterally spaced front cutting units as large as possible. Large gaps between the front cutting units are desirable to prevent various clearance and interference issues from arising with respect to the front cutting units when the front cutting units are put into a raised transport position. When the front cutting units are lifted into the raised transport position, the two side front cutting units tip in towards the middle front cutting unit as they lift off the ground such that the side front cutting units fold up along opposite sides of the mower. Thus, using large gaps between the front cutting units helps preclude the possibility that the side front cutting units could hit the middle front cutting unit as they are raised off the ground or that the side front cutting units could interfere with portions of their respective lift arms.
It would be an advance in the mower art to provide a reel type gang mower in which the streaks in the cut grass swath do not happen even in turns or in sidehill mowing. Desirably, however, this would be done without leading to any of the types of productivity and interference problems noted above.